Method of filling molds with fibrous material

ABSTRACT

The nonflowing molding materials are blown into the mold cavity which has a screen defining one surface of the article to be molded. The materials first fill up the remote areas of the cavity as the carrying air vents through the screen. As the cavity fills up to the feeding nozzle, a vent flap in the nozzle body opens up, allowing the carrying air to vent through the screened opening exposed by the flap until the mold is completely filled and the air is cut off.

States aterit 1 Munketal.

[ 51 Apr. w, 1973 [54] METHOD OF FILLING MOLDS WHTH FIBROUS MATERIAK[76] Inventors: Edmund Munk; Herbert Hess, both of In den Klaeren 25;Gerd Weinberg, Lerchenweg 14, all of Oberstenfeld, Germany [22] Filed:Oct. 7, 1970 [21] App]. No.: 78,959

Related US. Application Data [63] Continuation of Ser. No. 655,024, July21, 1967,

abandoned.

[30] Foreign Application Priority Data July 29, 1966 Germany ..F 49820[52] U.S. Cl. ..264/121, 141/67, 141/286, 164/200, 264/37, 302/36,302/59 [51] Int. Cl ..B65b 1/16, B65b 39/04 [561 References Cited UNITEDSTATES PATENTS 6/1907 White ..l4l/67 2,933,785 4/1960 Hansberg ..164/1603,099,045 7/1963 Honkanen ..264/ 349 3,165,570 1/1965 Deutsch ..264/l213,301,925 1/1967 Engel ..264/37 3,338,999 8/1967 Knapp ..264/1213,341,890 9/1967 Oja ..264/121 3,358,059 12/1967 Snyder ..264/1213,375,309 3/ 1968 Stevens ..264/121 Primary ExaminerDonald J. ArnoldAssistant ExaminerA. l-l. Koeckert Attorney-Michael S. Striker [5 7ABSTRACT The nonflowing molding materials are blown into the mold cavitywhich has a screen defining one surface of the article to be molded. Thematerials first fill up the remote areas of the cavity as the carryingair vents through the screen. As the cavity fills up to the feedingnozzle, a vent flap in the nozzle body opens up, allowing the carryingair to vent through the screened opening exposed by the flap until themold is completely filled and the air is cut off.

6 Claims, 8 Drawing Figures PATUHEG 3.726.954

E Fig-8 INVENTORS EDMUND HUNK HERBERT HAAS GERD WEINBERG ATTORNEY METHODOF FILLING MOLDS WITH FIBROUS MATERIAL This is a continuation of Ser.No. 655,024, filed July 21, i967, and now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to a method and apparatus for filling molds andespecially molds of an intricate shape with nonflowing moldingmaterials, particularly comminuted organic fibrous materials which aremixed with suitable binders, for example, heatsetting synthetic resins.

2. Description of the Prior Art Prior to this invention, molds of thistype have usually been filled by hand. This had, however, thedisadvantage that even the operation of filling molds of a relativelysimple shape required a considerable length of time and that it waspractically impossible to distribute the molding mixture in the mold soas to have the desired uniform density at all points.

Mechanical filling devices for such molds have also been developedwherein the molding material after passing through an arrangement ofrotating spiked rollers is filled at a steady rate through a funnel intothe mold. By making these spiked rollers of a suitable design anddimensions, by providing them in a suitable arrangement and driving themat a suitable speed, it is possible to treat the molding material to acertain extent in accordance with its different layer thicknesses so asto attain a substantially homogeneous molded body. Although this methodmay be satisfactory for properly filling molds of a simple shape, itdoes not produce any satisfactory results if the molds are of anintricate shape, since it may often occur that the molding mixture willnot pass with the required uniform density into more remote anddifficultly accessible parts of such a mold. Furthermore, the mechanicaleffort of carrying out this method and the expense for the necessaryapparatus, as well as the amount of space such apparatus requires, arevery considerable.

Attempts have also been made to attain a uniform filling of the mold byvibration, shaking or jarring. These methods and especially that ofvibrating the mold are, however, applicable only to lighter molds andhardly, if at all, to large and heavy molds. Furthermore, especiallywhen applying the vibration method, vibration nodes will occur whichcause the molding material to settle into certain shapes; Shakingand-vibrating a mold also result in a separating effect whereby thecoarser and finer particles become more or less separated from eachother or are sorted according to their degree of fineness. The materialwill then either be distributed in accordance with the shapes caused bythe vibration nodes or the coarse particles willbe brought up to theupper surface of the mold. Particularly the last-mentioned effect is,however, very undesirable if the molded bodies should have the smoothestpossible outer surface, for example, for being provided with adecorative coating.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a method and an apparatus for distributing a nonflowing moldingmixture consisting of comminuted fibrous materials and a suitableheatsetting binder as uniformly and quickly as possible in a mold, andespecially in a mold of an intricate shape. For attaining this object,the invention provides that the nonflowing molding material is blownfrom a suitable point into the mold in such a manner that the materialwill be progressively deposited within the area to be filled and atfirst at the remotest or most difficultly accessible parts of the moldfrom which it will then be progressively added to all other points so asto accumulate gradually in the direction toward the point where it isblown into the mold until the entire mold chamber is filled with moldingmixture.

The features and advantages of the present invention will become moreclearly apparent from the following detailed description thereof whichis to be read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a purely diagrammaticillustration of an apparatus for carrying out the method according tothe invention;

FIG. 2 shows a top view of the blast nozzle as employed in the apparatusaccording to FIG. 1;

FIG. 3 shows a top view of a mold which is connected to an apparatusaccording to FIG. 1;

FIG. 4 shows a vertical longitudinal section which is taken along theline IV-IV of FIG. 3;

FIG. 5 shows a vertical cross section which is taken along the line V-Vof FIG. 3; while FIGS. 6 to 8 show parts of cover plates of differentshapes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, FIG. I showsvery diagrammatically an apparatus for carrying out the inventivemethod. For producing a three-dimensional molded object, a female mold lis provided. Laterally acting plungers 1a, lb, 10, which are movable ina horizontal direction, are moved outwardly so that the entire moldcavity which is to be filled between the core part of the-mold andthe'lateral plungers la, lb, 1c, is empty. The male mold 2 acting fromabove is moved upwardly for such a distance that the female mold l iseasily accessible from above. This 'mold is then covered by a screen oran orifice plate 3.

This screen or orifice plate 3 is spaced from the core part of the moldat such a, distance that between this screen or orifice plate 3 and theupper surface of the core part the distance will be produced whichcorresponds to the required layer thickness of the molding mixture whichis to be applied above the upper surface of the core part. Of course,this distance may be made adjustable in accordance with the particularresults to be attained.

The molding material consisting of a mixture of comminuted organicfibers and a binder is located in the upper chamber 4 of a supply binwhich is'separated from its lower chamber 4' by a gate 5 in the natureof a bucket wheel. This gate which may be turned constantly orintermittently either by hand or mechanically at a variable speed, forexample, in the direction as shown by the arrow a, is adapted to conveythe molding material at the required speed and in the desired amount tothe lower chamber 4'.

By means of the blower 6, air of a certain pressure is blown through thechannel 7 in the direction of the arrow b into the lower chamber 4 ofthe storage bin and is then conducted in the direction of the arrowthrough a flexible channel 8 to the nozzle 9 which may be inserted intoa suitable aperture 10 in the wall of the female mold 1.

The bucket-wheel gate 5 prevents the air which flows under pressure intothe lower chamber 4' from escaping upwardly into the storage bin 4, andby its rotation it conveys the molding mixture into the lower chamber4'. The air current which enters the lower chamber 4 through the channel7 and then flows through the channel 8 in the direction of the arrow 0conveys the molding mixture which has been passed into this chamber bythe rotary gate 5 through the nozzle 9 to the inside of mold 1 where dueto the velocity of the air current this mixture is at first conveyed toand deposited in the most remote parts of the mold chamber, while theair escapes through the screen or orifice plate 3 to the outside. Theparticles of the molding material which are injected by the air currentare then deposited progressively from the most remote places of the moldchamber upon the particles which are already deposited so that thematerial gradually accumulates in the direction toward the blastaperture 10 until the mold is completely filled.

In this manner it is possible to fill even a mold of the most intricateshape absolutely uniformly, that is, at a uniform density of the moldingmaterial and without leaving any unfilled spaces. After the female moldhas thus been completely filled, the blast nozzle 9 is removed and theinlet opening 10 is closed in any suitable manner and the sceen ororifice plate 3 is lifted off the female mold and the male mold 2 ismoved into the latter from above. The molding operation may be carriedout in the conventional manner and it is then possible either to producea premolded blank by cold molding or a finished article by simultaneousheating. 1

In order to fill the mold properly up to the mouth of the nozzle 9 or upto the inlet opening 10, an apertur may be provided in the wall of thenozzle which may be closed by a hinged flap 9, as shown in FIG. 2.Underneath this flap 9', the aperture is covered by a relativelyfine-meshed wire screen which prevents the molding material fromescaping. Thus, the molding material may be filled uniformly into themold up to the nozzle opening since the increasing back pressure of theair will open the flap 9 so that the air can escape as soon as the molditself is completely filled and the air can no longer pass through themold and out through the openings in the screen or the orifice plate 3.

FIGS. 3, 4, and 5 illustrate the filling operation of a mold or a moreintricate shape. FIG. 3 shows a top view of the female mold when thecovering screen or orifice plate 3 is removed for clarity and at a timeshortly after the filling operation has been started. FIG. 4 shows avertical section of the same mold which is taken along the line IV-lV ofFIG. 3, while FIG. 5 shows a vertical section of the same mold which istaken along the line VV of FIG. 3.

The mold as illustrated in FIGS. 3 to 5 serves for producing a moldedarticle which consists of a flat upper wall, a flat end wall extendingat a right angle thereto, and two opposite side walls and rib-shapedcorrugations. The side of the article opposite to the end wall as wellas the lower side remain open. The molding material which has alreadybeen deposited in the mold is indicated by dots. The density at whichthese dots are spaced from each other is not intended to indicate thedensity of the deposited material but merely the thickness of theparticular layer of the material as seen in the direction in which it isdeposited.

The solid part of the female mold 1 consists of a core which isconnected above and at the sides to the surfaces 1' which limit theedges of the open sides of the body to be formed and also serve asguides for the different movable plungers 1a, lb, and 1c and the malemold 2 coming from above. The blast nozzle 9 is inserted into theaperture 10 in plunger 10 which after the nozzle 9 is removed is filledout for the molding operation by a suitable closure member.

For filling the mold, the air current which takes the molding materialalong in the direction of the arrow 0 is blown under a suitable pressureor a suitable velocity into the mold and carries the particles of thematerial to the remotest corners of the mold where because of the suddenchange in direction of the air current these particles are deposited bythe centricfugal force and then progressively accumulate toward thenozzle 9 and thereby build up the material to form a cohesive uniformfilling. After the particles are deposited, the air escapes through thescreen or orifice plate 3. The air currents are indicated in thedrawings by small arrows. These drawings also indicate how the moldingmaterial is built up at the same time from the bottom and the rear ofthe mold until the latter is filled completely.

Of course, the particular mold as herein described is only to beregarded as an example. The method according to the invention may beapplied in connection with any other mold which may be either of a stillmore intricate shape or of a very simple shape.

Instead of placing the screen or orifice plate upon the mold 1, asillustrated in FIG. 1, for example, by means of a frame 3' in which thescreen or orifice plate is adjustably mounted so as to project below thelower edge of the frame and to the inside of the mold, it is alsopossible to design the mold itself in such a manner that the screen ororifice plate rests on a shoulder 1" which is provided on the differentparts of the mold itself. The

aperture 10 for the nozzle 9 may be made of any shape and provided inany position in accordance with the particular requirements of the moldwhich is to be filled. Thus, for example, it does not have to beprovided on a lateral edge of the mold as illustrated but it may also belocated within one of the limiting surfaces, for example, the upperlimiting surface substantially at the center thereof. The angle at whichthe molding material is blown into the mold or at which the nozzle isinserted into the mold may also be varied in accorance with theparticular prevailing conditions, especially if the inlet opening or thenozzle is located at a lateral edge of the mold. If the nozzle isinserted at the center of one of the lateral surfaces or of the upper oreven the lower surface, its axis should preferably extend at a rightangle to this surface.

In the particular embodiment as illustrated it is assumed that thenozzle which increases in width toward its outlet opening has a flatshape so that the edges of the outlet opening form approximately anoblong rectangle. Of course, the nozzle may also be made of any othersuitable shape so that the edges of the outlet opening form, forexample, an elongated oval or a circle.

When employing an orifice plate in place of a screen, the advantage isattained that the apertures through which the air passes may have alarger diameter than in a screen so that the danger that these aperturesmay be clogged is considerably reduced. Furthermore, the arrangement,the diameter and the spaces between the apertures may be adapted to theparticular conditions of the mold, for example, in such a manner that bya suitable distribution of the apertures at such points where sharpcorners are to be provided in the mold, a 1

turbulence of the air current will be avoided which carries the moldingmaterial to be deposited. The ratio between the apertures and the solidparts between them may therefore be made unequal at different points. Ifdesired, it is also possible when using such an orifice plate to controlthe filling operation by covering some of the apertures.

Of course, the screen or the orifice plate, the distance of which fromthe inner limiting surface of the mold may, as already stated, beadjustable in accordance with the desired thickness of the molded layer,may also be inserted not from above but from one of the sides in placeof a fully withdrawn plunger. The screen or orifice plate may also havea profiled moved entirely to different molds. In other cases it may benecesary to associate the filling device in a fixed position with asingle mold, for example, when by means of this filling method theentire filling and mold- 5 ing operation including the removal of thefinished article from the mold is to be carried out automatically. Assoon as the filling operation has been completed, which may be checked,for example, by opening the mentioned flap 9, the part of the fillingdevice which is directly connected to the mold, as well as the screen ororifice plate and the suction device should then be lifted off orpivoted away from the mold for the following molding operation in orderto permit the particular male mold or plunger which for the fillingoperation was moved away then to be inserted into the mold. After themolding operation and after the finished molded article has been removedfrom the mold, the movable parts of the filling device, for example, apart of the supply channel, the nozzle, and the screen or orifice plateincluding the suction device, are again pivoted toward the mold andinserted therein, whereupon a new filling operation may be carried out.

The method according'to the invention insures that even molds of anintricate shape will be filled and packed at all points uniformly andhomogeneously with the molding material. The new method has the furtheradvantage over the conventional manual filling method that it will becarried out within a much shorter length shape if, for example, therespective outer surface of of time. Over the known filling methods bymechanical the molded body should have a certain profile. E amples ofsuch a screen or orifice plate 3 are illustratld in FIGS. 6 to 8. InFIG. 8, the orifice plate is reinforced by a reinforcing rib 3" whichextends transverse to", the longitudinal direction of the profiles.

By varying the air pressure which is produced by; the blower and thusthe velocity of the air current, it is possible to vary and control anddensity of the filling of the mold. l

The air which emerges through the apertures in the screen or orificeplate, and which, of course, takes along a certain amount of fineparticles, may preferably be sucked off by means of a suction device,not shown, and be returned into the storage bin 4. In this manner it ispossible to reduce the degree of comtamination of the surroundingatmosphere and to recover the fine particles which are taken along bythe discharged air.

In place of the embodiment of the invention as illustrated in FIG. 1, inwhich the molding material is fed to the air current after the latteralready passes under pressure and at a certain velocity from the blowerinto thelower part of the storage bin, it is possible to provide theblower between the storage bin and the mold. In this case, the moldingmaterial will first be sucked up by the blower, be conducted togetherwith the air current through the blower, be accelerated, and then beblown under pressure and at the required velocity into the mold.

When carrying out the method in actual practice it may in some cases beadvisable to make the required filling device of a movable constructionso as to permit it to be employed alternately for filling differentmolds. For this purpose, it may, for example, be mounted in a fixedposition and be pivotable or adjustable in association with severalfixed molds for filling them one after the other, or it may be mountedon a carriage for being means such as spiked rollers or the like theapparatus for carrying out the inventive method has the advantage ofrequiring considerably less space and of being less expensive.Furthermore, the method according to the invention also has theadvantage over the known methods that especially the fine material isconveyed to the points adjacent to the apertures, i.e., to the outersurface which defines the molded object. This means that the outer finematerial results in a less porous and very smooth and fine outer surfaceof the finished article which is especially of importance if thissurface is to be coated with a decorative layer.

A still further very important advantage of the method according to theinvention is the fact that it may be employed for carrying out thesuccessive steps of the production of molded parts even of a veryintricate shape fully automatically, that is, from the time of fillingthe molding material into the mold up to the ejection of the finishedmolded article. As a matter of fact, such a fully automatic operationcannot be carried out, except by employing the filling operationaccording to the invention.

Of course, the different possibilities of arranging the necessaryappliances for carrying out the method acthe interior of said cavity andan outer surface facing the surrounding atmosphere; admitting into saidcavity through said inlet conduit a stream of pressurized gas having thefibrous material entrained therein venting the gas through saidscreening device so that fibrous material is deposited progressivelyfrom those portions of the cavity which are most remote from said inletconduit until the material gradually accumulates in the directiontowards said inlet conduit; and terminating admission of said stream byventing the gas at said inlet conduit through a venting aperture whichis normally closed but opens in response to increased pressure in saidinlet conduit shortly before said cavity is complete charged.

2. In a method as defined in claim 1, wherein the step of admitting saidstream comprises inserting into said inlet conduit'a removable nozzle,and placing said nozzle in communication with a source of saidpressurized gas and fibrous material.

3. The method as defined in claim 1 wherein said stream of gas andfibrous material further includes a thermosetting binder material.

4. In a method as defined in claim 1; and further comprising the step ofso configurating said screening device that the same inparts to thesurface of said charge with which it is juxtaposed, a predeterminedcontour.

5. In a method as defined in claim 1, wherein the step of admitting saidstream comprises providing a supply of said fibrous material, andintroducing quantities of said fibrous material into a flow of saidpressurized gas.

6. In a method as defined in claim 5; and further comprising the step ofreturning to said supply such fibrous material as may still be entrainedin the gas vented through said screening device.

1. In a method of filling molds for pressure molding of fibrousmaterial, the steps of providing a female mold having a cavity open atone end and an inlet conduit communicating with said cavity; placingacross said open end of said cavity a screening device of predeterminedoutline having an inner surface facing the interior of said cavity andan outer surface facing the surrounding atmosphere; admitting into saidcavity through said inlet conduit a stream of pressurized gas having thefibrous material entrained therein venting the gas through saidscreening device so that fibrous material is deposited progressivelyfrom those portions of the cavity which are most remote from said inletconduit until the material gradually accumulates in the directiontowards said inlet conduit; and terminating admission of said stream byventing the gas at said inlet conduit through a venting aperture whichis normally closed but opens in response to increased pressure in saidinlet conduit shortly before said cavity is complete charged.
 2. In amethod as defined in claim 1, wherein the step of admitting said streamcomprises inserting into said inlet conduit a removable nozzle, andplacing said nozzle in communication with a source of said pressurizedgas and fibrous material.
 3. The method as defined in claim 1 whereinsaid stream of gas and fibrous material further includes a thermosettingbinder material.
 4. In a method as defined in claim 1; and furthercomprising the step of so configurating said screening device that thesame inparts to the surface of said charge with which it is juxtaposed,a predetermined contour.
 5. In a method as defined in claim 1, whereinthe step of admitting said stream comprises providing a supply of saidfibrous material, and introducing quantities of said fibrous materialinto a flow of said pressurized gas.
 6. In a method as defined in claim5; and further comprising the step of returning to said supply suchfibrous material as may still be entrained in the gas vented throughsaid screening device.